Synthesis of Optically Enriched Spirocyclic Benzofuran-2-ones by Bifunctional Thiourea-Base Catalyzed Double-Michael Addition of Benzofuran-2-ones to Dienones
A highly enantioselective catalytic double‐Michael addition reaction of substituted benzofuran‐2‐ones with divinyl ketones promoted by readily accessible tertiary amine–thiourea Cinchona alkaloids has been developed. A number of opticallyenrichedspirocyclic benzofuran‐2‐ones were prepared in very good yields (up to 99 %), diastereoselectivities (up to 19:1 d.r.), and very good enantioselectivities
Multiple approaches to enantiopure spirocyclic benzofuranones using organocatalytic cascade reactions
作者:Carlo Cassani、Xu Tian、Eduardo C. Escudero-Adán、Paolo Melchiorre
DOI:10.1039/c0cc01957g
日期:——
Three distinct aminocatalytic cascadereactions leading to enantiomerically pure spirocyclic benzofuranones have been devised, highlighting the ability of organocascade to generate high degrees of stereochemical and architectural complexity in a single chemical transformation.